Yeah, no-one can know exactly what the tools for A3 are going to look like yet, but they'll probably be different in a whole slew of ways, so I wouldn't go ahead and start configuring things just yet unless you want to do a lot repeat work.
What you can do however is modelling. As far as I know you can import various formats into O2, including 3DS Max and such, so any work you do with that + with textures is likely to be fully useable once the tools are out.
This is all conjecture of course, but that's the way it's worked before!
Wolfrug out.